Modem on hold

ABSTRACT

A modem to modem communication system supports call waiting services by exchanging hold request and acknowledge signals before relinquishing the line servicing incoming calls. Thereafter, the modem to modem session is reestablished without having to redial. The hold request may be denied or accepted, and may define the duration a modem will hold before hanging up. The holding modem maintains the session by fooling the higher protocol layers, making them believe that the modem is not on hold. Three-way calling services are also used to free up the shared line for outgoing calls while maintaining the session with holding modems. A table may be employed to screen incoming calls through a comparison of the caller ID information with that in the table. The table may be within the modem or the host computer.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Application Ser. No.09/394,018 (filed Sep. 10, 1999), now U.S. Pat. No. 6,768,791 which isitself a continuation-in-part of U.S. patent application Ser. No.09/361,842 (filed Jul. 27, 1999), now U.S. Pat. No. 6,819,749 whichclaims the benefit of U.S. Provisional Patent Application Ser. No.60/128,874 (filed Apr. 12, 1999). These applications are herebyincorporated herein by reference in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to the field of modem to modem datacommunication; and, more specifically, it relates to a modem to modemcommunication and three-way calling and call waiting telephony services.

2. Description of Related Art

A conventional communication system typically establishes an Internetdata session through a local and a remote ISP (Internet ServiceProvider) modem via a telephone switching network. Similarly, othermodem to modem communication uses the telephone switching network as thecommunication link. Such modems often share a single telephone line withother local telephony devices, e.g., telephones, facsimile machines,answering machines, etc.

To handle multiple incoming calls, telephone switching networks offerthree-way calling and call waiting services. Such services can beaccessed through manual interaction of a person using a telephone.Telephone switching networks have also added caller identification(caller ID) services to support call waiting. Thus, the person using thetelephone may view the caller ID before deciding to accept an incomingcall during a ongoing telephone conversation.

To maintain a data session between modems, continuous modem connectionmust be maintained during the data session. If after a period of timethe modem signaling is lost, modems will conclude that the data sessionhas been terminated and will disconnect.

When a telephone call waiting tone (indicating the presence of callerID) is detected during a local modem to remote modem data session, adecoding process involving both the local modem and a telephoneswitching network CO (Central Office) may be undertaken to retrieve thecaller ID. During the caller ID decoding process, however, the remotemodem usually disconnects. Thus, the remote modem must be redialed toreestablish and continue the data session.

If the local modem does not attempt to decode the caller ID, the callwaiting signaling will, at a minimum, interfere with ongoingcommunication and may cause the modems to hang up or retrain. Thus, thetelephone switching network provides a mechanism for turning on and offthe call waiting service. Before beginning the modem to modem datasession, the call waiting service is turned off for the duration of thesession. However, doing so prevents a user from receiving any otherincoming calls on a shared telephone line. As a result, users are forcedto add dedicated telephone lines for each type of telephony device intheir premises.

Further disadvantages of the related art will become apparent to oneskilled in the art through comparison of the related art with thedrawings and the remainder of the specification.

SUMMARY OF THE INVENTION

Various aspects of the present invention can be found in a communicationsystem having a telephone network that delivers call waiting signalingupon detecting an incoming call. The communication system comprising aremote modem and a local modem communicatively coupled thereto. Thelocal modem, which shares access to the telephone network, detects callwaiting signaling and directs the remote modem to enter a hold mode thentemporarily relinquishes access to the telephone network.

The local modem may also perform caller identification processing duringthis process. If so, the caller identification information may be usedto determine whether to service incoming calls. Making suchdetermination may involve providing a user interface, or may beperformed automatically by a computer coupled to the local modem.

Although unnecessary, the remote modem may remain in the hold mode forno longer than a predetermined interval. Other variations are alsopossible. For example, the local modem may use a ν.42 protocol to set upa secondary channel for signaling the remote modem regarding the holdmode. A table might be used that stores pre-selected calleridentification information for comparison with caller identificationinformation associated with incoming calls. Such comparison may be usedto determine whether to service incoming calls.

The remote and local modem attempt to maintain the communication sessionset up between the device housing the remote modem and the devicehousing the local modem. The remote modem must maintain the appearanceof a connection to the upper layer protocols even though the connectionto the local modem has been temporarily removed. Similarly, the localmodem must maintain the appearance of the connection to the networkingprotocols using the communication capabilities of the local modem. Tocarry this out, the remote modem may communicate with upper protocollayers of the network connection with manufactured data while in thehold mode. The local modem similarly maintains the appearance of anetwork connection with the application requiring the data bymanufacturing data and presenting it to the network stack while the twomodems are on hold.

These and other aspects of the present invention may also be found in acommunication system comprising a local link, a telephony device, aremote and a local modem. Therein, the telephony device is coupled tothe local link and may access the link when it is relinquished by thelocal modem. Specifically, the local modem establishes -a data sessionwith the remote modem by dialing a telephone number associated with theremote modem. After detecting a need to relinquish the local link to thetelephony device, the local modem directs the remote modem to maintainthe data session and temporarily relinquishes the local link to thetelephony device.

The local modem may reestablish the data session without redialing theassociated telephone number. Further variations are also possible. Forexample, the local modem may identify the need to relinquish the locallink to the telephony device by detecting: a) call waiting signaling, b)a user initiated request, or c) a request that is automaticallygenerated by a computer coupled to the local modem. Three-way callingand call waiting services are used to support the telephony device.

Yet other aspects of the present invention will become apparent throughreference to the remainder of the specification including the claims setforth herein.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary modem to modemcommunication network supporting three-way calling, call waiting andcaller ID in accordance with various aspects of the present invention.

FIG. 2 is an exemplary schematic diagram of an Internet basedcommunication system build in accordance with the present inventionutilizing the functionality described in FIG. 1.

FIG. 3 is an exemplary embodiment of the communication system of FIG. 2,illustrating DCE signaling of an ISP to make the ISP caller ID aware.

FIG. 4 is an alternate exemplary embodiment of the communication systemof FIG. 3 that employs keep alive functionality to maintain continuousdata session.

FIG. 5 is a schematic diagram of a computing device 411 coupled to amodem 421 having a memory look up table, according to the presentinvention, and permitting call classification and functional assignmentprior to forwarding caller ID information to the computing device 411.

DETAILED DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary modem to modemcommunication network supporting three-way calling, call waiting andcaller ID in accordance with various aspects of the present invention.In particular, a modem 1 at a premises 3 establishes and maintainsongoing communication with a modem 11 at a premises 13 via a switchingnetwork 21. If either the modem 1 or the modem 11 detect a need totemporarily relinquish a telephone line 10 or a telephone line 17,respectively, such modem (local modem) communicates to the other (remotemodem) a request to hold for a predetermined period of time. Ifaccepted, the remote modem places itself on hold, awaiting either: (a)reestablishment of communication from the local modem, or (b) a time outof the predetermined period of time. After placing the remote modem onhold, the local modem will relinquish or at least offer to relinquishthe telephone line 10 or 17. Thereafter, when the telephone line 10 or17 becomes available, the local modem will automatically reestablishcommunication with the remote modem. If the predetermined period of timehas lapsed, the local modem will automatically call the remote modem.Otherwise, the local modem will reestablish communication by merelyaccessing the remote modem and engaging in a fast training sequencebefore carrying on where the modems 1 and 11 left off.

Either of the modems 1 and 11 can determine the need to relinquish theircorresponding telephone lines 10 and 17 by (a) receiving call waitingsignaling from the switching network 21, (b) detecting a local extensionoff hook, (c) receiving user input via computing devices 5 or 15, and(d) detecting a need from the associated computing device 5 or 15. When,for example, the modem 1 receives call waiting signaling from theswitching network 21 (due to an incoming call from a telephony device 31at a premises 33), the modem 1 communicates a request to hold to themodem 11.

If the modem 11 honors the request, the modem 11 begins waiting forreestablishment of the data session by the modem 1 for a firstpredetermined period (e.g., 30 seconds), and the modem I interacts withthe switching network 21 to retrieve the caller ID information (ifconfigured to do so) and presents an indication of the incoming call,along with caller ID information if employed, via a screen (not shown)on the computing device 5. The computing device 5 may signal a user bysimulating a ring signal and delivering a pop-up window containing thecaller ID information.

If the user fails to accept the incoming call or rejects such call, themodem I will reestablish communication with modem 11 before the firstpredetermined period lapses. If however the user wants to take the call,the user interacts to accept the call via the computing device 5. Themodem 1 responds by communicating a second predetermined hold period(e.g., 30 minutes) to the modem 11 and then “flashes” the telephone line10. The switching network 21 responds by connecting the incoming call tothe telephone line 10. Thereafter, the user is free to use a telephonydevice 7 or 9, e.g., a telephone, facsimile machine, answering machine,etc., to service the incoming call. When the telephony device 7 or 9hangs up, the modem 1 “flashes” the telephone line 10. The switchingnetwork 21 again communicatively couples the telephone lines 10 and 17,and the modem 1 reestablishes communication with the modem 11.Alternatively, if the telephony device 31 disconnects prior to the modem1 “flashing,” the switching network 21 again communicatively couples thetelephone lines 10 and 17, and the modem 1 reestablishes communicationwith the modem 11. Had the first predetermined time period lapsed beforethe second predetermined period was communicated or had the secondpredetermined time period lapsed before the modem 1 reestablishedcommunication, the modem 1 would automatically dial or redial the modem11 to reestablish the link.

Instead of or in addition to signaling a user via the computing device105, the modem 1 may also deliver a ring signal or other such indicationdirectly to the attached telephony device 7 or to the locally connectedtelephone device 9 via the telephone line 10. The modem 11 performssimilar functionality in its interaction with the computing device 15and the telephony device 19 when receiving an incoming call via callwaiting services.

The modem 11 may also detect the need to relinquish the telephone line10 by detecting a local extension off hook event from either thetelephony device 7 or 9. For example, when the telephony device 7happens to comprise a telephone, the modem 1 detects when a user liftsthe receiver of the telephony device 7 and, in response, communicates ahold request to the modem 11 and establishes a three-way call dial tonethrough interaction with the switching network 21. The user may thenestablish an outgoing call. When the telephony device 7 hangs up, themodem 1 using the three-way calling service features reestablishes thelink via the switching network 21 to the modem 11 without having toredial.

A user may also interact via the computing device 5 to request gainingaccess to the telephone line 10. For example, the user may desire tosend a fax from a telephony device 9. The modem 1 responds to such arequest by establishing a hold condition with the modem 11 and usingthree-way calling functionality to gain a dial tone on the telephoneline 10. Thereafter, the modem 1 communicates via the computing deviceto the user that the telephone line 10 is free for use by the telephonydevice 9. When the telephony device 9 disconnects or the remote sidedisconnects, the modem 1 again can reestablish the communication linkwith the modem 11 without having to redial.

Similar functionality also occurs automatically without userinteraction. For example, a computing device 5 may periodically gainaccess to the telephony device 31 to service a communication exchangewith the telephony device 31.

In addition, the modem 1 may place the modem 11 on hold to permit thetelephony device 7 or 9 to communicate with the telephony device 19. Inthis way, the primary communication link between the modems 1 and 11might be used to set up the secondary communication link between thetelephony devices 7 or 9 and 19.

The switching network 21 may comprise one or more central offices (COs)interconnected by a toll network. The telephone lines 10 or 17 maycomprise twisted pair, cable, fiber and/or wireless links, for example.

The modem 1 and the computing device 5 may be separate or integrated.Similarly, the modem 11 may be internal to the computing device 15 orexternal.

FIG. 2 is an exemplary schematic diagram of an Internet basedcommunication system built in accordance with the present inventionutilizing the functionality described in FIG. 1. More specifically, aclient modem 103 that services a client computer 101 establishes andmaintains a data connection with an ISP (Internet Service Provider)modem 125 of an ISP computing system 107.

A user wishing to establish the data session between the client computer101 and the Internet 113, employs client modem 103 that dials through atelephone network 105 to an ISP modem 125. The ISP modem 125 providesaccess to the ISP 107 that participates via a link 127C on the Internet113.

During the existence of the data communication link, the telephonenetwork 105 may receive a telephone call from, for example, a telephone119. In response, the telephone network 105 delivers call waitingsignals to the client modem 103. On detecting a call waiting tone, theclient modem 103 signals the ISP modem 125 regarding the presence ofcaller identification. In one embodiment, the client modem instructs theISP modem 125 to maintain the communication link for a firstpredetermined period of time. In another, the ISP modem 125 either willwait indefinitely or will have a preset predetermined period which neednot be communicated. The client modem 103 next coordinates with thetelephone network 105 to receive and decode the caller identification.The caller identification is forwarded to the user via a display on theclient modem 103 (if external), and/or on the client computer 101. Inturn, based on the caller identification, the user determines whether toterminate the existing data session or ignore the incoming telephonecall and return to the existing data session, all within the firstpredetermined period. If the user fails to act or chooses to reject theincoming call, the client modem 103 will reestablish communication withthe ISP modem 125. If the user chooses to accept the call, and if thefirst predetermined period is not long enough, the client modem 103 willcommunicate a second predetermined period, e.g., 30 minutes, to the ISPmodem 125. Thereafter, the client modem 103 “flashes” the telephonenetwork and signals the user via the client computer 101 as previouslydiscussed and/or, if so configured, via the line 127. The telephonenetwork 105 responds by connecting the incoming call to a line 127. Theuser may then employ a facsimile device 119 or a voice mail or voicestorage system 121, for example, to service the incoming call.

The ISP modem 125 may also be placed on hold by the client computer 101,either through manual user interaction or automatically to meet a needthat arises. For example, a user may desire to use the telephone 149during an ongoing session between the ISP modem 125 and the client modem203. The user interacts via a window on the computing device 101 toplace such request. In response, the computing device 101 directs theclient modem 103 to place the session on hold.

As before, the client modem 103 communicates a hold request to the ISPmodem 125 which may choose to honor the request. If refused, theconnection is terminated. If honored, the ISP modem 125 is placed onhold, and the telephone network 105 is signaled to begin three-waycalling services. The telephone network 105 provides a dial tone and theclient modem 103 directs the computing device 101 to display a readyindication. Thereafter, the user may employ the telephone 149 to placethe call.

All other modes of employing three-way calling and call waiting servicesdescribed in reference to FIG. 1 are also possible. In all cases, theISP modem 125 and the client modem 123 both communicate with upperlayers of the protocol stack to ensure that the session is maintained.Thus, even though the session is actually placed on hold, neither theapplication software nor the higher protocol stack layers need to beaware of such condition, even though they might be modified to do so.

A point to point data session may exist between the client computer 101and a computer 117. The data session is established after a modemhandshake following a dial up routine between the client modem 103 and amodem 123. Caller ID information/call waiting and three-way callingfunctionality are similarly processed as referenced above.

Additional features of the client modem 103 permits the direction ofboth faxes received from a fax modem 121 and voice mail received from avoice storage 119. A client computer 109 is connected to the Internet113 via a cable network 111. A cable modem 130A enables the connectionof the client computer 109 and the Internet 113 connectivity and furtherconstitutes part of a communication network 100.

Communication links 127A and 127B couple the client modems 103 and 123with the telephone network 105. The communication links 127A and 127Bcomprise twisted pair wiring but may also or alternatively comprise aradio communication link, for example, or may be ISDN, ADSL, or DSL, forexample.

Cable modems may be employed which utilize similar functionality.Specifically, a cable modem 130 couples with a computing device 109 viaa network interface card 129. A computing device 101 may directly couplewith the cable modem 130 via the telephone network 105 and the cablenetwork 111. If a need arises to relinquish the line 127B, e.g., anincoming call is detected by the computing device 101. The computingdevice 101 sends a hold request to the cable modem 130 which, in turn,“spots” the upper layers of its protocol stack to act like the sessionis ongoing and begins waiting. As before, the client modem 103relinquishes the link 127B to servicing the need and, when completed,the client modem 103 reestablishes the session with the cable modem 130without having to redial.

In a further embodiment, a CO within the telephone network 105 providesan “attention signal” to both the client modem 103 and the ISP modem 125when, for example, the client modem 103 and the ISP modem 125 areengaged in ongoing communication. The “attention signal” would convey apending request to at least temporarily change the “ownership” of thetelephone line 127B. In such an embodiment, the client modem 103 neednot inform the ISP modem 125 that it is considering relinquishing thetelephone line 127B.

The CO within the telephone network has been modified to deliver a dialtone while not dropping the second line. Thus, when the client modem 103detects an extension-off hook condition, e.g., the telephone 149 ispicked up, the client modem 101 first signals the ISP modem 125 to gointo a hold mode. Next, the client modem 103 requests that the COgenerate a dial tone and relinquishes the line to the telephone 149.

In such embodiments as well as the other described herein, call waitingindications, with or without caller ID services are “attention signals.”Attention signals are those signals that convey to a modem that arequest for another use for a shared telephone line is present. Anotherexample beyond call waiting might be an operator's manual attempts tointerrupt an ongoing session in emergency situations. In mostembodiments, attention signals are delivered only to the modem whoseline is to be shared, yet, as described above, need not be the case.Such attention signals can also be delivered to all parties and modemsor telephony devices participating in an ongoing communication exchange.

Additionally, the ISP modem 125 might send a hold request to the clientmodem 103. While the client modem 103 is on hold, the ISP 107 can changethe routing of the ISP modem 125, substitute another ISP modemautomatically (for example when ISP modem 125 is having problems or isnot optional for the client modem 103), etc. This may all happen withoutever relinquishing any telephone link.

The aforementioned functionality also supports Internet browserinteroperability. For example, when interacting with a browser runningon the computing device 101 to surf the Internet, a user may encounter atelephone number on a web page that they would like to call. Byselecting a “place call” button on the browser, the computing device 101delivers an “attention signal” to the client modem 103 which, in turn,places itself and the ISP modem 125 in a hold mode. Before entering thehold mode, the client modem 103 may also dial the number and if soconfigured and pursuant to meta information provided in the web page,may interact with the answering party or system to assist the user inreaching a desired location within the receiving party's answeringsystem. Whether or not such additional services are provided by theclient modem 103, the computing device 101 then delivers a signal to theuser to pick up the telephone 149.

FIG. 3 is an exemplary embodiment of the communication system of FIG. 2,illustrating DCE signaling of an ISP to make the ISP caller ID aware.More specifically, using a secondary channel 217, a client modem 201signals an ISP modem 221 to make the ISP modem 221 aware when a callwaiting signaling is received.

A user utilizing the client modem 201 engages in a data session on aprimary channel 215 with an ISP modem 221 via a telephone network 219.When a call waiting tone is detected during the data session, callwaiting detect circuitry 207 informs a processing circuitry 203 that anincoming telephone call has been detected. In response, the processingcircuit 203 signals the ISP modem 221 informing of the call waitingevent. The processing circuitry 203 then utilizes a secondary channel217 to signal the ISP modem 221 to refrain from disconnecting while theISP modem 221 decodes the received caller identification information. Inresponse, the ISP modem 221 may choose to accept by transmitting anacknowledgment signal.

After receiving the acknowledgement, the processing circuitry 203performs caller ID processing to retrieve the caller ID information fromthe telephone network 219. Specifically, the processing circuitry 201transmits a DTMF tone to a central office (CO) within the telephonenetwork directing that the caller ID information be forwarded. The COthen transmits a Bell 211 signal having the caller ID information (whilemuting the data session line connected to the ISP modem 221). Theprocessing circuit switches from its current protocol, typically V.90 tothe Bell 212 mode and receives the caller ID information. The caller IDinformation is presented to the user through a LCD display within theclient modem 201 or through a pop-up window generated by the user'ssoftware, for example, and requesting whether the user wishes to acceptor reject the incoming call.

In one embodiment, if the user accepts the incoming call, the ISP modem221 retains the data session connection for a predetermined time whilethe client modem 201 is engaged with the incoming call. On returning,the client modem 201 resynchronization with the ISP modem 221 tocontinue the prior data session, that is, the client modem 201 and theISP modem 221 go through timing synchronization, train echo cancellersand transmit known signal conditions, for example. If after theexpiration of the predetermined interval, the client modem 201 fails toreturn, the data connection is terminated.

In an alternate embodiment, the user may accept the incoming call whilethe ISP modem 221 is instructed to idle. When the client modem 201returns, a fast resynchronization algorithm is used to re-establishcommunication more rapid because prior line conditions are known, andboth modems need not go through full retraining. Further detailregarding “resynchronization” can be found in U.S. patent applicationSer. No. 09/361,842 (filed Jul. 27, 1999) and entitled “Method andApparatus for Fast V90 Modem Startup,” Attorney Docket Nos. 99RSS181 and50944.4700; and U.S. Application Ser. No.09/394,018 (filed Sep. 10,1999) and entitled “Method and Apparatus for Quick Modem Reconnect.”These applications are hereby incorporated herein by reference in theirentirety.

Another functionality previously described with reference to FIGS. 1-2also apply for interactions between the client modem 201 and the ISPmodem 221. In addition, the client modem 201 may employ a look up tableas further referenced in FIG. 5 to determine how and whether to servicean incoming call.

The secondary channel 217 is a virtual channel set up using the V.42protocol. This is a proprietary mode in which both the client modem 201and the ISP modem 221 communicate their capabilities and exchangeinformation through the secondary channel 217. The processing circuitry203 employs software, hardware and firmware to direct and synchronizevarious tasks relating to the client modem 201. Although described inreference to ISP communication, such functionality also applies outsideof that context.

FIG. 4 is an alternate exemplary embodiment of the communication systemof FIG. 3 that employs keep alive functionality to maintain continuousdata session. Specifically, the ISP modem 321 employs a keep alivefunction 323 which delivers “keep alive packets” to higher protocolwhether or not the client modem 301 sends a hold request.

Particularly, there are several layers of protocol involved in theconnection between a user's Internet browser, for example and an ISP,and these layers have to be “kept alive” while the client modem 301relinquishes a link 331 for call waiting services or otherwise. During adata session, while the client modem 301 has relinquished the link 331,the higher protocol layer, for example, TCP/IP, may encounter a time outcondition and terminate the data session.

To achieve a continuous data session, when caller ID is received, thebottom two layers namely, the physical and the data link layer,responsible for transmission, framing, and error control of thecommunications link may be modified. In one embodiment, the keep alivefunctionality 323 within the ISP modem 321 transmits “keep alive” packetstreams to the higher TCP/IP protocol layer after the modem signal isinterrupted. This deceives the higher TCP/IP layers and prevents thesession from terminating. The “keep alive” packet stream may be eitherdata bits or control signals or both, and located within the clientmodem 301, the ISP modem 321 or both.

Again, the keep alive stream need not require a hold request to be used.In fact, in one embodiment, the ISP modem uses the keep alive wheneverit is having difficulty reaching the client modem 301 for whateverreason. The stream is used for a predetermined period to allowreestablishment of the link during a period that far needs a traditionalsession termination period.

FIG. 5 is a schematic diagram of a computing device 411 coupled to amodem 421 having a memory look up table, according to the presentinvention, and permitting call classification and functional assignmentprior to forwarding caller ID information to the computing device 411.The computing device 411 comprises a processing circuit 413 and otherconventional circuitry such as an interface circuit 415.

The processing circuit 413 operates pursuant to a plurality ofapplications (e.g., a first and second application 417 and 419) thatindependently service incoming calls via the modem 421. A controlapplication 423 selectively interacts to launch the plurality ofapplications.

The modem 421 comprises a processing circuit 431 and a memory 433, amongother circuitry. The modem 421 determines whether to forward the callerID information to the computing device 411 based on a table 435 withinthe memory 433. The table 435 stores a series of caller ID crossreference entries. Thus, for example, upon detecting an incoming call,the modem 421 notifies an ISP modem (not shown) that it is about tointerrupt the present modem connection to receive caller ID information.When the caller ID information is received, the processing circuit 431stores the caller ID information in a buffer 437 and compares thatinformation with the entries in the table 435.

If a match is found, the processing circuit 431 informs the ISP modemthat delivers the buffered caller ID information to the computing device411 to the control application 423 which, in turn, launches theappropriate application that has been designated to service the receivedcaller ID information. The caller ID information may also be forwardedto such application.

If no match is found, the modem 421 will ignore the incoming call andcontinue the data session with the ISP modem. Thus, the modem 421 neednot involve the computing device 411 or bother the user by forwardingcaller ID information unless it has been assigned to do so via theentries in the table 435. In this embodiment, the:table is used toforward only those incoming calls that have a table entry. However, inalternate embodiments the table may be used to screen out matchingincoming calls.

The user via computing device 411 loads the table 435 with, for example,telephone numbers of incoming calls to be processed by the first andsecond applications 417 and 419. In an exemplary embodiment, the firstapplication 417 comprises facsimile processing software, while thesecond application 419 comprises data processing software. If facsimiletransmissions are only to be received from a single telephone number,that telephone number is loaded into the table 435 of the modem 421,similarly, the telephone numbers from which data transmissions will bereceived are also loaded into the memory 435. When a facsimiletransmission is received from the telephone number stored in the table435, the processing circuitry 431 delivers the caller ID information tothe computing device 411, and immediately switches to the facsimiletransmission without user interference.

Thereafter, the control application 423 directs the first application417 in handling the transmission. When the facsimile transmission iscompleted, the control application 423 cooperates with the modem 421 toreturn the user to the prior data session. When an incoming datatransmission is received from a corresponding telephone number stored inthe table 435, the processing circuit 431 delivers the calleridentification to the computing device 411 for processing by the secondapplication 419, for example. Calls from telephone numbers that are notcontained in the table 435 may be ignored by the modem 421.

Alternatively, or in addition, the table may be loaded with caller IDinformation that identifies telephone numbers to be ignored and notanswered by the DCE/DTE. For example, known voice telephone numbers maybe ignored by the DCE 421 while all other non-tabled numbers would beanswered by the DCE 421.

Thus, by screening and/or the selection of specific calls, the DCE isable to save time expended by the user in determining which telephonecalls to accept. In addition, a single telephone line may be shared by aplurality of communication devices, such as the DCE 421 and other DCEsor telephones. Further, such screening and/or filtering may also beemployed to remove unnecessary call processing burdens from an activeDTE which may be engaged in other tasks. Thus, for example, thecomputing device 411 during a data session need not have to shareprocessing resources to service calls not intended for the computingdevice 411.

Although the table 435 is shown to be stored within the modem 421, itmight be alternatively be stored within the computing device 411. Insuch embodiments (not shown), the computing device 411 stillautomatically filters unwanted incoming calls.

Although a system and method according to the present invention has beendescribed in connection with the preferred embodiment, it is notintended to be limited to the specific form set forth herein, but on thecontrary, it is intended to cover such alternatives, modifications, andequivalents, as can be reasonably included within the spirit and scopeof the invention as defined by the appended claims.

1. A first modem for communication with a second modem over acommunication channel, said first modem being in communication with ahandset, said first modem comprising: an off-hook detector capable ofdetecting said handset going off-hook, while said first modem is incommunication with said second modem, and further being capable ofgenerating an attention signal in response thereto; and a transmittercapable of transmitting a hold request to said second modem in responseto said attention signal; wherein said handset is placed off-hook by auser for dialing an outgoing call, and wherein said communicationbetween said modems over said communication channel ceases for a periodof time after transmitting said hold request, and wherein said firstmodem keeps an upper layer protocol alive during said period of time bymanufacturing data and presenting said data to an upper layer tomaintain an appearance of receiving said data from said second modem. 2.The first modem of claim 1, wherein said hold request includes saidperiod of time.
 3. The first modem of claim 1, wherein said hold requestis transmitted using a secondary channel.
 4. The first modem of 1,wherein said first modem receives an acknowledgement in response to saidhold request.
 5. The first modem of claim 1, wherein a dial tone isprovided to said handset after said communication between said modemsover said communication channel ceases.
 6. The first modem of claim 1,wherein a modem signal used for data communication between said firstmodem and said second modem is interrupted after said transmittertransmits said hold request to said second modem.
 7. A communicationmethod for use between a first modem and a second modem in communicationover a communication channel, said first modem being in communicationwith a handset, said communication method comprising the steps of:detecting said handset going off-hook; transmitting a hold request tosaid second modem in response to said handset going off-hook; ceasingsaid communication with said second modem over said communicationchannel by said first modem for a period of time; causing a dial tone tobe generated for dialing an outgoing call using said handset; andkeeping an upper layer protocol alive during said period of time bymanufacturing data and presenting said data to an upper layer tomaintain an appearance of receiving said data from said second modem. 8.The communication method of claim 7, wherein said hold request includessaid period of time.
 9. The communication method of claim 7, whereinsaid transmitting step uses a secondary channel for transmitting saidhold request.
 10. The communication method of claim 7, furthercomprising the step of receiving an acknowledgement in response to saidhold request.
 11. The communication method of claim 7, wherein a modemsignal used for data communication between said first modem and saidsecond modem is interrupted after said transmitting step.
 12. A firstmodem capable of communicating with a second modem over a communicationchannel, a portion of said communication channel existing over atelephone line between said first modem and a central office, said firstmodem comprising: a receiver capable of receiving a relinquishmentrequest, while said telephone line is in use by said first modem forcommunication with said second modem, to relinquish said use of saidtelephone line; and a transmitter capable of transmitting a hold requestto said second modem to place said communication between said modems onhold; wherein said communication between said modems is placed on holdand said use of said telephone line is relinquished, and wherein saidfirst modem causes a dial tone to be generated over said telephone lineafter said communication between said moderns is placed on hold, andwherein said first modem keeps an upper layer protocol alive while saidmodems are on hold by manufacturing data and presenting said data to anupper layer to maintain an appearance of receiving said data from saidsecond modem.
 13. The first modem of claim 12, wherein a handset sharessaid telephone line with said first modem, and wherein saidrelinquishment request is received as a result of said handset goingoff-hook.
 14. The first modem of claim 12, wherein said relinquishmentrequest is received as a result of instructing said first modem to diala number.
 15. The first modem of claim 12, wherein a third device sharessaid telephone line with said first modem, and wherein saidrelinquishment request is received from said third device.
 16. The firstmodem of claim 15, wherein said third device places a call on saidtelephone line.
 17. The first modem of claim 12, wherein said dial toneis received as a result of using a three-way call feature supported bysaid central office.
 18. A method of sharing a telephone line for use bya first modem, said first modem being in communication with a secondmodem over a communication channel, a portion of said communicationchannel existing over said telephone line between said first modem and acentral office, said method comprising: receiving a relinquishmentrequest, while said telephone line is in use by said first modem forcommunication with said second modem, to relinquish said use of saidtelephone line; transmitting a hold request to said second modem toplace said communication between said modems on hold; placing saidcommunication between said modems on hold; keeping an upper layerprotocol alive by manufacturing data and presenting said data to anupper layer to maintain an appearance of receiving said data from saidsecond modem; relinquishing said use of said telephone line; and causinga dial tone to be generated over said telephone line.
 19. The method ofclaim 18, wherein a handset shares said telephone line with said firstmodem, and wherein said relinquishment request is received as a resultof said handset going off-hook.
 20. The method of claim 18, wherein saidrelinquishment request is received as a result of instructing said firstmodem to dial a number.
 21. The method of claim 18, wherein a thirddevice shares said telephone line with said first modem, and whereinsaid relinquishment request is received from said third device.
 22. Themethod of claim 21, wherein said third device places a call on saidtelephone line.
 23. The method of claim 18, wherein said dial tone isreceived as a result of using a three-way call feature supported by saidcentral office.